The Aarushi murder trial has received the attention of India because it is a story at the heart of which is something all Indians marvel about: our nation’s diversity.

We are a diverse people in terms of class, caste, religion, region—and language—and in every act of this tragedy, diversity and differences have had an impact on what we call “the system”.

The accused couple—well-to-do dentists—ran into the conflict that diversity inevitably engenders, at an early stage of the murder investigation. They were accused of killing their daughter for “honour”, a concept supposedly alien to the educated middle-class.

On Friday, the issue of diversity was felt at a base level: S.P.R. Prasad, the DNA expert from the Centre for DNA Fingerprinting and Diagnostics (CDFD, Hyderabad), was being cross-examined. The court’s problem was that he had very little Hindi—the language of record in Ghaziabad.

Questions and answers had to be repeated several times. The loss of time was evident, the loss in translation is something that we will never be able to measure. Prasad isn’t the only one in the case who has presented such a problem to the court. It has had an issue with two other key witnesses. The Talwars’ temporary maid, Bharti, who was the first person on the scene early on the morning of 16 May 2008, is from Malda, West Bengal. Confounded by the questions put to her in Hindi, she blurted out that she had told the court what she had been schooled to say by the prosecution.

The forensic scientist Dr B.K. Mohapatra’s cross-examination took a comical turn because of yet another facet of diversity—the accent with which Indians from different regions speak English or Hindi. The court spent a considerable amount of time figuring out what Mohapatra, a native of Orissa, meant when he said “blawed” (blood).

It may have taken longer than expected, but the importance of Friday’s cross-examination cannot be underestimated. The technical examiner of the samples sent to the CDFD, Prasad’s testimony stands like a resolute guard at the door of acquittal for the Talwars.

Prasad represents the CDFD in defending what is a very dubious action on the lab’s part. The CDFD has said that there was a typographical error in one of its reports, which it rectified through a letter written two years after the fact.

The original had clear evidence of the involvement of one of the Talwars’ employees, Krishna, in the murders of Aarushi and the Talwar’s servant Hemraj. The “corrected” report erased that possibility.

Dr G.V. Rao, a DNA scientist formerly of the CDFD, says that this kind of “rectification” is unacceptable. The CDFD learnt about the “error” not through its own processes, but via a letter from the CBI on 17 March 2011, more than two years after the error had been committed.

This letter arrived more than a week after the CBI had made up its mind that an error had been committed: the agency told the Allahabad High Court this even before the CDFD had issued any clarification, leave alone followed the process that such a serious rectification requires.

The CDFD is supposed to be India’s premier DNA testing lab—it’s fame partly due to the sterling work done on Basmati rice—and a higher standard is expected of it, says Rao. The Talwars have engaged the scientist as a consultant.

The CDFD’s brief is to follow the highest international standards. Rao cites an example from Singapore in April 2012, where a typographical error was committed during labeling in a DNA lab. The person responsible was sacked instantly, and all 800 samples from the period in question were sent for retesting.

“Can we have the same standards here?”, asks Rao.

By then, however, they had been summoned as the accused. In a matter of one week in March 2011, a curious, critical twist came into play. It was a typo, said the CBI. Hemraj’s blood was not on Krishna’s pillow cover. The CDFD findings pertaining to Hemraj’s and Krishna’s bedding were accidentally swapped by some clerk typing the report.

The CBI sought, and got, a clarification from India’s best known forensic lab that this had indeed happened. The defence now wants to know how. It has prayed to the trial court to have all documents pertaining to the correction/clarification placed on record. Along with those relating to the actual processes followed during tests.

It is evident that the CBI wrote a letter to the CDFD asking them to clarify exactly, and only, whether there was a typo in this specific instance. There was no mention of other parts of the report in the letter the investigating agency sent. It is not clear how the CDFD was able to ascertain its typists had indeed made a mistake—the actual samples were not with the lab, so there was no question of retesting. Neither did the lab address the larger issue that arose out of this: was this the only typo? Could there have been other critical clerical errors that might prove to be the difference between innocence and guilt, life and death?

The prosecution is in no mood to supply the documents that get to the root of the “error”. But the defence has argued that not only can it not examine the CDFD forensic scientists appearing as prosecution witnesses effectively if it does not have all the information on record, these papers also have implications for the cross examination of the investigating officers of the CBI who dealt with the “swap”.

The Talwars’ application calls the integrity of both the CBI and the CDFD into question, so the importance of the records can hardly be overstated. The trial judge will decide on Saturday whether or not to ask the prosecution to place the papers before the court.

Avirook Sen has been a journalist and writer for over 20 years. A former resident editor of Hindustan Times (Mumbai) and editor of Mid-Day, he has written with passion and insight on subjects as varied as sport and terrorism for top publications across the world. His first book, Looking for America, was published in 2010 to enthusiastic reviews. You can write to him at avirook@gmail.com